With the development of the technologies of wireless communication and information processing, portable electronic devices such as mobile telephones and electronic notebooks are now in widespread use. These electronic devices enable consumers to enjoy the convenience of high technology services anytime and anywhere. Foldable electronic devices are particularly welcome by consumers for their convenience.
Generally, foldable electronic devices have most of the electronics in one housing, called the body. The other housing, called the cover, normally contains fewer electronic components than the body. Other foldable electronic devices have all the electronics in the body, with the cover containing no electronics. Various types of hinge assemblies are used to join a body and a cover of a foldable electronic device, so that the cover can unfold up from and fold down upon the body. Manufacturers are constantly seeking to reduce the volume, size and weight of portable foldable electronic devices. Thus, it is desirable that the hinge assembly coupling the main housing with the cover is modularized and miniaturized. A modularized hinge assembly has moving parts such as a cam member, a cam follower and a spring held together in a unified structure. The structure is easily and quickly attached to the main housing and the cover during mass production. A miniaturized hinge assembly has as few parts as possible, with the parts being as small as practicable.
One kind of portable cellular foldable electronic device with a hinge assembly is described in P.R. China Patent Application No. 03100445.8 published on Jul. 30, 2003. Referring to FIG. 6, the hinge assembly includes a housing 20, a rotary member 30, a rotary shaft 40, a moving part 50, and an elastic element 60. The housing 20 has a hole in one end thereof, and an opposite open end. The rotary member 30 has a connecting portion 31 and a cam follower 32. The connecting portion 31 defines a groove 33. A connecting wall (not shown) protrudes from the bottom of the groove 33. The connecting wall includes four fan-shaped walls (not shown). The rotary shaft 40 has a first portion 41 with a larger diameter, a flange 42, a second portion 43 with a smaller diameter, and a latching portion 44. The moving part 50 includes a sidewall 51, and a cam portion 52 engaging with the cam follower 32. The elastic element 60 is received in the housing 20, and pushes the moving part 50 toward the rotary member 30. The rotary shaft 40 passes through the hole of the housing 20, the elastic element 60, the moving part 50 and the rotary member 30 in that order. Then, the rotary shaft 40 is securely connected with the rotary member 30 by the connection between the latching portion 44 and the fan-shaped walls.
Although suitable for some foldable electronic devices, the above-described hinge assembly is not suitable for certain miniaturized foldable electronic devices. This is because the housing 20 of a miniaturized foldable electronic device may not have sufficient bulk to sturdily withstand the forces generated from the spring. In addition, the structure of the rotary member 30 of the hinge assembly is complicated and the volume of the rotary member 30 is large. This means that the longitudinal size of the hinge assembly is increased, and hence the volume of the foldable electronic device is increasing. Furthermore, the structure of the rotary shaft 40 is complicated, which increases the manufacturing costs of the hinge assembly.
What is needed, therefore, is a hinge assembly which has a relatively simple and small modularized configuration, and which can be produced at low cost.